The petroleum industry uses drilling rigs, derricks, and completion units (hereinafter generally referred to as "derricks") to drill and produce wells. Various types of oilfield tubulars, pump rods and other types of generally cylindrical and elongate equipment are conventionally lifted from a rack or other supporting equipment at or near the ground level to the elevated derrick floor, then are placed in the well for conducting drilling, completion, or stimulation operations. For example, drill pipe is typically added to a well in segmented intervals or joints until the drill pipe string reaches a designated depth in the well, and each pipe joint must be raised from a rack at the ground floor to the elevated derrick floor in order to be grasped by an elevator then run into the well. The oilfield equipment is generally removed from the well at a later date, and is conventionally supported on the rig floor and then lowered back to the rack or other supporting equipment at the ground level. As a further example, production casing is run into the well to a selected depth after a well is drilled. This casing is relatively heavy and cumbersome, and a large number of man hours are expended positioning casing joints onto the derrick floor for a run-in operation. Oilfield tubulars are repeatedly taken out of a hole and placed on a pipe rack, and then tripped back into the hole for conducting petroleum recovery operations.
After production casing is set in a well, various types of generally cylindrical and elongate tools may be run into the wellbore for evaluation purposes, including reservoir testing and cased hole logging tools. In many instances, these test tools are heavy and cumbersome to physically lift and maneuver onto the derrick floor. Crew members commonly experience back injuries while lifting or manipulating this equipment to its desired position on the derrick floor, and expensive oilfield equipment is frequently damaged during this operation. Production rods are also frequently placed within the tubing of a well to facilitate pumping of hydrocarbons from the downhole formation. These production rods are commonly also manually lifted and positioned on the derrick floor for running into and out of the well.
A continuing problem in the well drilling and completion industry is physical injury to oilfield crew members resulting from the manual lifting and positioning of tubulars or other equipment to the desired position on the derrick floor. Some reports indicate that over 40% of injuries to oilfield workers occur as a result of lifting and positioning tubulars and other equipment. Oilfield injuries resulting from these operations decrease the efficiency of the hydrocarbon recovery operations and significantly increase the overall cost of these operations. This pervasive problem is compounded by inadequate levels of experienced oilfield workers in many locations, and results in delayed development of petroleum reserves throughout the world. Serious accidents frequently occur as tubulars and other oilfield equipment are lifted from the ground level position to the derrick floor, and have resulted in severe injury to numerous crew members.
While various systems have been devised for positioning oilfield tubulars, production rods, and other equipment onto the derrick floor, these systems are comparatively slow and thus are not widely used. Lengthy time delays to safely position equipment on the derrick floor are unacceptable to both the well operator and to the crew members. Equipment at a well site may rent for tens of thousands of dollars per day, and any procedure which slows down the run-in or trip-out operation is avoided. Various types of oilfield equipment lifting systems have been devised which utilize a wire rope which extends in a loop from the ground level to the derrick floor and to the top of the derrick, and then back to the ground level. An elongate trough may be secured at each end to the cable and tubulars or other equipment placed in the trough, then the cable pulled along its loop to raise the trough and the equipment to the derrick floor. In addition to being slow and cumbersome, this wire rope equipment typically still requires a great deal of physical effort by multiple crewmen to properly position the oilfield equipment at its desired location on the derrick floor. Also, this wire rope arrangement creates its own safety risks, and is not favored by many oilfield crew members.
U.S. Pat. No. 3,503,401 discloses drill pipe handling equipment which employs a complex arrangement of lifting hydraulic rams to elevate an inclined platform which supports a drill pipe. Once the platform is inclined at its desired level, a hydraulic ejection ram pulls drill pipe onto the derrick floor by lateral movement of a plate relative to the platform. The ejection plate sweeps the entire platform surface when positioning a tubular onto the derrick floor. The ejection ram cylinder is mounted at the forward or elevated end of the platform, and thus the hydraulic lifting rams must be sized for also raising the weight of the ejection ram with the platform to its desired inclination. When initially loading a tubular onto the. horizontal platform, the platform is raised several feet off the ground, and accordingly the drill pipe cannot be easily rolled from a low level pipe rack or other support onto the platform. The equipment as disclosed in the '401 patent is also difficult to assemble and disassemble, and a great deal of time and cost is involved in setting up and taking down the equipment at the well site. The equipment as shown in this patent is thus not in common use for lifting tubulars to a derrick floor.
Equipment which has had some success in placing tubulars onto a derrick floor utilizes a singular tubular-conveying trough which is inclined or positioned from an initial horizontal position at the ground level to an inclined position such that the tubular may be pulled toward the derrick floor. Patents relating to such equipment include U.S. Pat. Nos. 3,559,821, 4,235,566, 4,347,082, 4,371,302, 4,379,676, 4,380,297, 4,382,738, 4,386,883, 4,403,898, 4,426,182, 4,453,872, 4,470,740, 4,474,520, and 4,486,137. The prior art thus discloses a trough for receiving a tubular which may then be inclined or elevated. A push member is commonly moved along the trough by a belt or chain mechanism for the purpose of pulling the tubular onto a derrick floor. The trough must first be inclined to a desired level and then the transport mechanism activated to move the tubular along the trough to the derrick floor. After the tubular is grabbed at the derrick floor, the trough must be lowered back to the ground level, and the process repeated with each tubular joint. These systems are used with some success, but the process is still unfortunately slow and time consuming. As a result, many oilfield workers continue to manually manipulate oilfield tubulars and related downhole equipment to position the equipment at its desired location on the derrick floor.
The disadvantages of the prior art are overcome by the present invention. An improved method and apparatus are hereinafter disclosed for easily and reliably positioning oilfield tubulars and other downhole equipment on the derrick floor. The system of the present invention significantly reduces accidents and injuries to crew members, and does not significantly slow down the run-in or trip-out operations.